Millions more Americans are now approved to use a potent anti-cancer vaccine — one that could save thousands of lives each year. It’s an important public health development but one that is frustratingly dogged by this question: Will complacency or anti-vaccine disinformation stop those newly eligible from taking advantage of this immunization?

The U.S. Food and Drug Administration’s recent approval of the Gardasil 9 vaccine’s expanded adult use is a dramatic step forward to protect new generations from potentially deadly cancers caused by the human papilloma virus (HPV). HPV infections can lead to cervical, vaginal and vulvar cancers in women, penile cancer in men, and throat and anal cancers in both genders.

HPV vaccines first became available beginning in 2006, but their use has been limited to older children, teens and young adults. On Oct. 5, the FDA dramatically expanded the use of one vaccine — Gardasil 9 — to include adults ages 27 through 45. The move makes sense.

HPV is common and easily spread through intimate contact. While it’s best to inoculate adolescents before they become sexually active, young and middle-aged adults should be protected as well. Many in the newly expanded age range for Gardasil 9 were too old to get the shot series when it first became available. But they’re often still dating or they may be leaving a marriage and seeking new partners, potentially putting them at risk of acquiring HPV.

This infection’s risk should not be underestimated. About 12,000 American women a year develop cervical cancer caused by HPV, and roughly 4,000 women a year die from it. More than 50,000 Americans are diagnosed with mouth or throat cancer annually, with this type of cancer being twice as common in men as in women, according to the American Cancer Society. The organization notes: “There’s been an ongoing rise in cases of oropharyngeal cancer linked to HPV in both men and women.”

Pessimism about the public’s embrace of vaccine is based on parents’ reluctance to protect their children from HPV. Vaccination rates often regrettably lag far behind more traditional childhood shots. In Minnesota, 77 percent of adolescents aged 13 through 17 have had one or more doses of the tetanus-diphtheria-pertussis vaccine. Only 52 percent had started the HPV series of shots and just 34 percent had completed either a two- or three-shot series, according to the Minnesota Immunization Information Connection.

The HPV numbers are disappointing, and it’s concerning that rural rates often lag urban areas. Misunderstandings bear some responsibility. Many parents may not realize HPV’s link to many types of cancer, and others wrongly believe the vaccine will encourage promiscuity because it protects against a sexually transmitted virus. By that faulty logic, teens shouldn’t wear seat belts either because doing so will encourage reckless driving.

The disinformation campaign waged by vaccine conspiracy theorists has played a role, too. HPV vaccines are often targeted on social media, where the solid science backing their safety is ignored. Those concerned about side effects — the most common being pain at the injection site, fever, headache, joint paint and nausea — should talk with a doctor. It’s reckless to rely instead on information from a blog or meme.

That’s good advice for those in the expanded HPV vaccine age group, too. The responsible step is to protect yourself and others from a virus that can cause cancer. In Australia, screening programs and widespread support for HPV vaccines have put the nation on track to reduce cervical cancer cases so dramatically that the disease could effectively be “eliminated as a public health problem” in the next 20 years, according to a recent report in the Lancet Public Health Journal.